1. Field of the Invention
The subject invention relates to a constant velocity joint, and more specifically to a fixed center constant velocity joint.
2. Description of the Related Art
Fixed center constant velocity joints typically comprise an outer member, which defines a spherical interior and a plurality of outer member ball tracks within the interior. The interior and the plurality of outer member ball tracks extend along a longitudinal axis. The plurality of outer member ball tracks includes a first group of outer member ball tracks and a second group of outer member ball tracks. An inner member is disposed within the interior, and defines a spherical outer surface and a plurality of inner member ball tracks extending along the longitudinal axis. The plurality of inner member ball tracks includes a first group of inner member ball tracks and a second group of inner member ball tracks. The first group of inner member ball tracks opposes the first group of outer member ball tracks, diverging from one another in a first axial direction to define a first group of funnels. The second group of inner member ball tracks opposes the second group of outer member ball tracks to define a second group of funnels. The constant velocity joint further comprises a plurality of drive balls, with one of the drive balls disposed within each of the first group of funnels and within each of the second group of funnels. A cage is disposed between the outer member and the inner member, and defines a plurality of windows. One of the drive balls is disposed within each of the windows.
Typically, the first group of funnels and the second group of funnels include a diverging width, which urges the drive ball contained within each of the funnels in the direction of the diverging funnel. The first group of funnels and the second group of funnels may be arranged so that the funnels all diverge in the same direction, or may be arranged so that the first group of funnels and the second group of funnels diverge in opposing directions. U.S. Pat. No. 6,848,999 to Weckerling et al. discloses a fixed center constant velocity joint in which the first group of funnels diverge in an opposite direction from the second group of funnels, with the first group of funnels and the second group of funnels spaced radially about the longitudinal axis in an alternating relationship.
The diverging configuration of the funnels urges the drive balls in the direction in which the funnel diverges. The cage acts against the drive balls to resist the movement of the drive balls. Accordingly, it is said that the drive balls steer the cage, i.e., pre-load the cage to de-lash the joint and keep the cage from rattling. However, a significant amount of heat is generated by friction caused by the interaction between the cage and the drive balls as the cage resists movement of the drive balls.